Anchor group for monolayers of organic compounds on metal and component produced therewith by means of organic electronics

ABSTRACT

An anchor group anchors organic dielectric compounds used in the production of organically based capacitors. The capacitors referred to are those that can be produced in a parallel process on a prepeg or other common printed circuit board substrate without additional metallization on copper. The pre-fabricated capacitor layer can then be built into the printed circuit board, thereby gaining on space and cost for the surface of the printed circuit board.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to InternationalApplication No. PCT/EP2009/061323 filed on Sep. 2, 2009 and GermanApplication Nos. 10 2008 048 446.6 filed on Sep. 23, 2008 and 10 2009016 659.9 filed on Apr. 7, 2009, the contents of which are herebyincorporated by reference.

BACKGROUND

Organic dielectric or conductive compounds on metal electrodes,especially on copper layers or copper-containing layers, are used, forexample, in the production of organic-based electronic components.

For the purposes of miniaturization, it is particularly advantageous touse ultrathin layers, especially monolayers, with precisely adjustedfunctionality in electronic components, especially also in organicelectronic components. In order that molecules in monolayersself-organize and hence exhibit maximum functionality and functiondensity, it is advisable to fix them on the particular electrodes byhead or anchor groups, which automatically results in an alignment ofthe linker groups, i.e. of the groups connecting the two ends. Theattachment to the substrate takes place spontaneously provided that thesubstrate has been prepared appropriately.

The specific functionality is determined by the linkers and head groups.The anchor determines the self-organization.

For this purpose, DE 10 2004 005 082, for example, discloses an aromatichead group which has π-π interaction and whose introduction ischemically complex, which binds a self-assembled dielectric layer to anelectrode. According to DE 10 2004 005 082, the attachment to thecounterelectrode used, as what is called the anchor group of the organicdielectric compound, which is usable as a monolayer in a capacitor, is asilane compound which can be attached to the electrode via an oxidelayer formed from a non-copper oxide.

A disadvantage of the known related art is that the electrode surface,i.e., for example, the copper surface, preferably has to befunctionalized with aluminum or titanium for application of theself-assembled monolayer, the functionalization then providing an oxidicsurface for attachment. However, such a functionalization step for theelectrode surface is very costly, since non-copper metals first have tobe applied and structured. An additional factor is that the electrodesurfaces, if they are processed by conventional methods on conventionalblanks or circuit boards or prepregs generally have a surface roughnessin the region of approx. 4 μm. This roughness limits the mechanicalstability of a surface coated with a monolayer, since the gaps at theparticle boundaries are not necessarily fully covered, or high fieldstrengths arise at substrate tips. The height of the monolayer,generally approx. 2 to 5 nm, and not more than 20 nm, does not planarizethe roughness due to the conforming deposition.

SUMMARY

It is therefore one potential object to overcome the disadvantages ofthe related art and more particularly to provide an anchor group for aself-assembled monolayer (SAM), which enables application of the SAMcoating to a copper electrode produced and prepared by conventionalmethods.

Accordingly, the inventors propose an organic compound for aself-assembled monolayer on a copper layer or copper-containing layer,comprising at least one anchor group for a first electrode layer, alinker group and a head group for attachment to the next layers, whereinthe anchor group contains at least one phosphonic acid and/or aphosphonic acid derivative. The head group may be of a specific type, orelse be dispensed with. In addition, the inventors propose a componentwhich is based on organic electronics and is integrated into a circuitboard, a prepreg or a blank, wherein the blank, circuit board or prepregserves as a substrate on which an organic compound for a self-assembledmonolayer according to the subject matter of the proposals (see above)is formed.

An “organic compound for a self-assembled monolayer” refers above tocompounds which, due to a particular anchor group, are aligned in thelayer such that a majority of the molecules are present with paralleland/or identical alignment in the layer. For example, DE 10 2004 005082describes corresponding organic compounds which can form monolayers inthe dielectric layer of a component based on organic electronics. Theorganic compounds usable differ from these at least by a different headand/or anchor group. In addition, many commercially available materialscan be employed and used to produce impervious monolayers.

In an advantageous embodiment, a component based on organic electronicsis formed directly on a blank, for example a copper blank produced bycustomary production methods, without having been functionalized by afurther metal or smoothed by specific processes. The metal layer towhich the anchor group is applied is accordingly a copper layer orcopper-containing layer, the proportion of copper in the layer beingpreferably more than 10%, especially preferably more than 40% and mostpreferably more than 70%, measured in mole percent.

There is no need for a separate preparation of the substrate surface.The preparation includes only cleaning steps and not the application ofadditional materials, as is customary according to the art.

A useful component based on organic electronics is especially acapacitor. In addition, it is possible by virtue of the inventors'proposals to improve, for example, organic field-effect transistors, thegate dielectric for organic field-effect transistors being suitable fordirect integration into the circuit board, or organic light-emittingdiodes (OLEDs), the electrodes for the OLEDs being deposited on the thininsulation, especially since the copper layer for top-emitting OLEDs ishermetic. The term “OLED” also includes light-emitting electrochemicalcells (LEECs).

Finally, analogously to the structure for the OLEDs, the layer sequencecan also be used for solar cells, and so possible components based onorganic electronics are, as well as capacitors, at least also organicfield-effect transistors, OLEDs and organic solar cells. In principle,the proposals are suitable for all kinds of organic insulatingintermediate layers. The layer can also be applied only for a certaintime, i.e. temporarily. Applied in a temporary or permanent manner tocopper or copper alloys, the layer is also suitable as a printable“photoresist substitute”, or for production of regions of differenthydrophobicity.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome more apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 shows such a structure using the example of a capacitor.

FIG. 2 visualizes the roughness of a pickled circuit board substrate.

FIGS. 3 and 4 show the electrical characteristics (value approx. 10Ω andphase angle of the impedance approx. 0°) assuming all capacitors areshort-circuited.

FIG. 5 shows a spin curve, with the effective mean layer thickness ofthe polymer layer shown as a function of the spin speed.

FIG. 6 shows the dependence of the capacitance on the frequency.

FIG. 7 shows the dependence of the phase of the impedance on thefrequency.

FIG. 8 shows the dependence of the phase of the loss factor on thefrequency.

FIG. 9 shows the dependence of integration density 49 pF/mm² on thedirect current voltage applied for a capacitor having a nominalintegration density of 49 pF/mm².

FIGS. 10 to 13 show the dependence of the capacitance on the electrodearea at 0 V to 3 V at 50 pF/mm².

FIG. 14 shows the leakage current measurement for a capacitor with anintegration density of 50 pF/mm², for round electrodes.

FIG. 15 shows the leakage current measurement for a capacitor with anintegration density of 50 pF/mm², for angular electrodes.

FIG. 16 shows a roughness within the range from 0.20 nm to 0.33 nm.

FIG. 17 shows the homogeneity of vapor-deposited layers.

FIG. 18 shows the measurement to determine the relative dielectricconstants.

FIG. 19 shows the dependence of the capacitance on the frequency ofcapacitors with an integration density of 150 pF/mm²

FIG. 20 shows the dependence of the phase on the frequency of capacitorswith an integration density of 150 pF/mm²

FIG. 21 shows the dependence of the loss factor on the frequency ofcapacitors with an integration density of 150 pF/mm²

FIG. 22 shows the dependence of leakage current characteristics as afunction of voltage for different capacitors

FIG. 23 shows the resistance of the capacitor to DC current at differentintegration densities.

FIG. 24 shows the dependence of the contact angle measured after the SAMcoating of the circuit board on the insertion time of the sample in thesolution.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

In particular, it is possible to structure a component inexpensively anddirectly on a pickled copper surface. FIG. 1 shows such a structureusing the example of a capacitor.

The base material used for the capacitor is a copper blank pickled bycustomary methods with an applied layer of approx. 5-30 μm of copperplate and a roughness in the μm range. The pickling can be effected asusual by degreasing with organic solvents and then etching the surfacewith peroxodisulfates and sulfuric acid. FIG. 2 visualizes the roughnessof a pickled circuit board substrate.

The copper surface can be additionally cleaned, as usual inelectroplating technology, by cathodic means. For this purpose, thesubstrate is connected as the cathode in dilute sodium carbonatesolution and cleaned by the hydrogen which forms at a current flow of10-100 mA/cm².

As a result of the pickling, the contact angle with respect to water isless than 5°. As a result, the copper surface becomes very hydrophilic.To prevent the oxidation of the copper, and as a primer for thesubsequent thin polymer deposition which is planarized only locally, amonolayer of an organic phosphonic acid is deposited immediatelythereafter. The phosphonic acid anchor group has been found to be highlysuitable especially for copper, whereas DE10 2004 005082 B4 workedpreferably with silanes (working example), and the copper surfacepreferably has to be functionalized with aluminum or titanium fordeposition. Such a functionalization step for the copper surface isdispensed with completely in the component presented.

Preference is given to the long-chain phosphonic acids, such as decyl-to octadecylphosphonic acid, in general terms CH₃—(CH₂)_(n)—PO(OCH)₂,where n=8-25, preferably n=18. The molecule chain may also take the formof a polyether chain (—O—CH₂—CH₂—O—)_(m) where m is from 1 to 20,preferably from 2 to 10. The contact angle with respect to waterincreases after deposition of an octadecylphosphonic acid to >130° foralkylphosphonic acids, and is thus an indication of the quality of thedeposition. The alkyl chains may also be fully or partly fluorinated.

Alternatively, the deposition can also be effected via the phosphonicesters or salts thereof, or other derivatives such as amines etc. Thesalts can be obtained directly in solution by adding smaller orequivalent amounts of alkali (NaOH, KOH, ammonia or ammoniumhydroxides).

The head group used in the case of a support polymer may be singlybranched or unbranched alkyl groups, or alkenyl groups suitable forfurther reactions (i.e. crosslinking). To improve the attachment of themonolayer to the support polymer, the head group may be a fluorine,nitrile, amino, ester, aldehyde, epoxy or acid function. In the case ofa fluorination, the head group could comprise —CF₃, —CHF₂, —CH₂F.

To increase the mechanical stability, in an advantageous embodiment, asupport polymer, i.e. a thin polymer layer, is applied to the monolayerfor stabilization and/or for the local planarization of the capacitor orcomponent. Typically, an effective polymer layer thickness of approx.550-600 nm is obtained for an integration density of 50 pF/mm² at adielectric constant of 3.17, whereas an effective layer thickness of180-200 nm is obtained for an integration density of 150 pF/mm². Morepolymer is applied in the depressions, while a thinner polymer film ispresent at the peaks. Compared to the approach presented by 3M, thecomponent thickness of 14 μm can be lowered by a factor of 70 whilesimultaneously increasing the capacitance by a factor of 15.

The leakage current characteristics of the capacitor disclosed here aredetermined almost exclusively by the self-assembled monolayer. It wastherefore also measured (see FIG. 24) that the resistances have profilesindependent of the stabilization polymer thickness because the essentialcontribution to the ohmic overall resistance of the capacitor to directcurrent is made by the self-assembled monolayer. It is thereforepossible to planarize using any desired polymers, provided that they arecompatible with the circuit board processes.

For example, polyhydroxystyrene crosslinked by melamine-co-formaldehydewas used. A good planarizing action was achieved when thepolyhydroxystyrene had a molar mass in the range from 500 to 100 000,especially from 3500 to 50 000, especially preferably of 8000. Thecrosslinking was preferably performed within the temperature rangebetween 180° C.-230° C. After the crosslinking, the polymer layer formechanical stabilization is no longer attacked by solvents.

In addition to the novolac-like polymers, it is also possible for resinsbased on epoxides, acrylates, urethanes or carbonates to find use assupport polymers. Further polymers: polyesters, polyamides, polyimides,polybenzoxazoles, polyvinylidene difluoride (teflon-like materials ingeneral), polyvinyl compounds (carbazoles, alcohols and esters thereof).Copolymers or block copolymers such as ABS are likewise suitable. Themolar mass of the polymers may be in the range from 1000 to 1 000 000.

The locally planarized polymer layers may be applied as follows:

-   -   a. from solution. For this purpose, 1-50%, preferably 5-20%, of        the polymer with or without crosslinker is dissolved in an        organic solvent (PGMEA=propylene glycol monoethyl ether acetate,        tetrahydrofuran, dioxane, chlorobenzene, diethylene glycol        diethyl ether, diethylene glycol monoethyl ether,        gamma-butyrolactone, N-methylpyrrolidinone, ethoxyethanol,        xylene, toluene, etc), and applied in appropriate thickness by        spin-coating, printing (screen printing, inkjet printing,        spraying, etc). Thereafter, the solvent is evaporated by a heat        treatment step, which leaves the dust-dry or cured polymer        layer. The polymers can be crosslinked thermally or        photochemically. Crosslinking is optional. For polyvinyl        alcohol, for example, water is also suitable as a solvent.        Possible crosslinkers are photoacids.    -   b. In the case of acrylates and epoxides, the monomers or oligo        compounds can be applied by spin-coating or printing (see above)        and then crosslinked thermally or photochemically to give the        dielectric.

The outer electrodes used for the capacitor may be any metal or alloythereof, or conductive metallic printing pastes. Likewise suitable areorganic conductors, such as PEDOT (polystyrenesulfonic acid-dopedpolydiethoxythiophene) or PANI (camphorsulfonic acid-doped polyaniline).Particular preference is given, however, to the metals used in thecircuit board industry: copper, aluminum, nickel, gold and silver oralloys thereof. Metal counterelectrodes applied over the full area canbe structured thereafter by etching and mechanical ablation processes(laser) known to those skilled in the art. When several capacitors areprovided with a common counterelectrode, the counterelectrode can alsobe deposited from the gas phase by shadowmasks (see working examples).

The counterelectrodes can also be applied by electroless metallization,after local or full-area seeding. In principle, it is possible to useall processes in the circuit board industry, since the dielectric aftercrosslinking is compatible with the customary media in the circuit boardindustry.

The head group normally stabilizes the monolayer itself. In general, thehead group brings about the attachment of the SAMs to the oppositelayer. Attachment is understood here to mean any form of the bond,especially a chemical bond, which can range from a covalent double bondthrough ionic bonds up to simple van der Waals bonds.

The head group does not come into contact with the electrode in acapacitor with a stabilizing polymer outer layer, as envisaged in anadvantageous embodiment. Only the polymer layer comes into contact withthe outer electrode. The polymer layer can be functionalized by theknown processes, for example by metal application by vapor deposition orsputtering, printing with metal pastes, etc. It has been foundexperimentally that it is then also possible to dispense with aninconvenient head group. The interaction of the individual chains is inprinciple sufficient for the stabilization of the self-assembledmonolayer, but a head group can improve the electrical properties evenin the case of use of a polymer outer layer to stabilize the monolayer.

The envisaged structure of an electrode layer with a subsequentinsulator layer can of course be used advantageously not only in acapacitor, but is in principle also suitable for the followingapplications:

as

1. A gate dielectric for organic field-effect transistors for directintegration into the circuit board.

2. A substrate for top-emitting OLED (the copper layer is hermetic). Onthe thin insulation, it is then possible to deposit the electrodes forthe OLED.

3. Analogously to the structure for the OLEDs, the layer sequence isalso suitable for solar cells.

Example 1

For the test setup, an FR4 blank laminated with 30 μm of copper is cutto a size of 50×50 m². This is first freed of grease with acetone andisopropanol. A commercial photoresist (TMSR8900) is spun on at 6000 rpmfor 20 s and dried on a hotplate at 110° C. for 60 s. The photoresist isexposed for 7 s with UV light of a wavelength of 365 nm, and developedin aqueous alkaline developer for 60 s.

The photostructuring is followed by pickling in a 5% ammoniumperoxodisulfate solution at 40° C. for 3 min. After rinsing with waterand isopropanol, the blank is placed into a solution ofoctadecylphosphonic acid (0.2-0.25 g) in isopropanol (100 ml). After 12hours, the blank is rinsed with isopropanol and dried in a nitrogenstream at 100° C. for 1 min.

After the pickling, the contact angle with respect to water is 1° to 4°.After the deposition of the octadecylphosphonic acid, the contact angleis 135°, which suggests excellent coverage of the copper layer.Thereafter, 100 nm of aluminum is applied by vapor deposition through ashadowmask as the counterelectrode. For example, a processed capacitancespecimen was thus produced on an FR4 circuit board. The electricalcharacteristics (value approx. 10Ω and phase angle of the impedanceapprox. 0°) in FIGS. 3 and 4 show that all capacitors areshort-circuited. An ideal capacitor would have a volume resistance ofinfinity. 10 ohms is a short circuit, i.e. the capacitor does not work.It is found that, for standard circuit boards with a roughness in the μmrange without Ti or Al pretreatment or without the presence of anaromatic head group on the primer, the process from DE 10 2004 005082 isnot suitable for formation of capacitors in high yield.

Further examples show that high-capacitance capacitors can be formeddirectly on copper with a primer even without a head group with π-πinteraction, the introduction of which is chemically complex. The anchorgroup, i.e. the phosphonic acid group, resides directly on the coppersurface.

Example 2 Integration Density 50 pF/mm²

Analogously to example 1, a copper-laminated FR4 circuit board or aprepreg is coated with the primer octadecylphosphonic acid orhexadecylphosphonic acid. A solution of 0.8 g of polyvinyl-phenol (molarmass 8000) containing 0.2 g of polymelamine-co-formaldehyde crosslinkeris dissolved in 5.67 g of propylene glycol monomethyl ether acetate andspun on at 2500 rpm for 40 s, and predried on a hotplate at 100° C. for60 s. In a vacuum oven, the novolac-like polymer is cured with theformaldehyde crosslinker at 180° C. to 230° C. Thereafter, analogouslyto example 1, aluminum electrodes are applied by vapor deposition (basepressure 1*10⁻⁶ mbar). Other integration densities can be obtained byadjusting the spin speed.

FIG. 5 shows a spin curve, with the effective mean layer thickness ofthe polymer layer shown as a function of the spin speed.

FIGS. 6 to 9 show the dependence of the capacitance (6), of the phase ofthe impedance (7) and of the loss factor (8) of an actual capacitor withintegration density 49 pF/mm² (9) on the frequency and direct currentvoltage applied. The electrical characteristics are shown in FIGS. 6 to9. The dependence of the capacitance measured on the frequency is low,which demonstrates the quality of the capacitor presented. The phase ofthe impedance of the actual capacitor assumes values between −89° and−87° in the frequency range shown. The loss factor was in the region of0.0x and is, as shown in FIG. 8, likewise virtually independent of thefrequency. Moreover, there is no evident dependence of the parametersshown in FIGS. 6 to 9 on the direct current voltage applied. In themeasurements, bias voltages between 0 V and 3 V were set, while theamplitude of the superimposed alternating current, the frequency ofwhich was varied between 1 kHz and 1 MHz, was 0.1 V.

FIGS. 10 to 13 show the dependence of the capacitance on the electrodearea. The strictly linear behavior shows that large-area capacitances(20 mm²=1 nF) can also be produced. The yield of functioning substratesis 100% on a substrate according to example 1. The quality of thecapacitors is thus comparable to discrete SMD components (loss factor of0.035 in commercial ceramic SMD capacitors).

FIGS. 10 to 13 show the dependence of the capacitance on the electrodearea at 0 V to 3 V at 50 pF/mm².

FIGS. 14 and 15 show the leakage current measurement for a capacitorwith an integration density of 50 pF/mm² and (14) round or (15) angularelectrodes.

FIGS. 14 and 15 show the leakage current measured as a function of thedirect current voltage applied in capacitors with different electrodeareas. The measurement curves do not show an actual breakthrough, butmerely an increased leakage current from 7 V DC (2 nA to 4 nA), but thisis small compared to SMD components. Moreover, there is no evidentdependence of the currents measured in FIGS. 14 and 15 on the electrodeshape.

The dielectric constant of the crosslinked polymer was determined asfollows. Owing to the excessive roughness of the FR4 substrate (see FIG.2), an exact determination of the dielectric thickness is impossible.For this reason, capacitors were produced on a substrate with minimumroughness. For this purpose, glass substrates were used as carriers.With the aid of a profilometer, the profile of such a substrate wasfirst examined. FIG. 16 shows the roughness measurement on a glasssample.

As shown in FIG. 16, the roughness is within the range from 0.20 nm to0.33 nm. For the further characterization of the capacitors, bothelectrodes were applied to the substrate by a vapor deposition process.The homogeneity of the vapor-deposited layers is shown in FIG. 17.

A 100 nm-thick copper layer was applied by vapor deposition. The cornersof the glass sample were masked with Kapton tape as a shadowmask. Afterthe vapor deposition process, the Kapton tape was removed and the layerthickness was measured with the aid of a profilometer.

After the SAM had been vapor-deposited onto the substrate, the polymerlayer was applied by spin-coating (20% by weight polymer solution, spinspeed 2500 rpm). Before this processing step, the sample was providedagain with Kapton tape at one corner. This created a defined level atwhich the thickness of the dielectric can be determined. The subsequentlayer thickness measurement gave an effective mean thickness of 573 nm.With the aid of another vapor deposition step, the upper electrode ofthe capacitors was produced.

By plotting the capacitance measured as a function of the product ofelectrode area, dielectric constant for vacuum and the reciprocal of thedistance between the two capacitor plates, it is possible to determinethe relative dielectric constant graphically.

FIG. 18 shows the measurement to determine the relative dielectricconstants.

For the relative dielectric constants, the measurements described,taking account of the measurement uncertainties, were used to calculatea value of 3.17±0.08.

Example 3 Integration Density 150 pF/mm²

Analogously to example 1, a copper-laminated FR4 circuit board or aprepreg was coated with the primer octadecylphosphonic acid orhexadecylphosphonic acid. In order to preserve the adhesive propertiesof the prepreg, a photochemically crosslinking epoxy resin is used. Thephotocrosslinking is performed, for example, through a shadowmask. Afterthe uncrosslinked regions have been rinsed off, there remain defineddielectric regions. Contact sites are exposed.

In the case of the circuit board, a solution of 1 g of polyvinylphenol(molar mass 8000) containing 0.25 g of polymelamine-co-formaldehydecrosslinker is dissolved in 8.75 g of propylene glycol monomethyl etheracetate and spun on at 2000 rpm for 40 s, and predried on a hotplate at100° C. for 60 s. In a vacuum oven, the novolac-like polymer is curedwith the formaldehyde crosslinker. Thereafter, analogously to example 1,aluminum electrodes are applied by vapor deposition (base pressure1*10⁻⁶ mbar).

In another embodiment, the counterelectrode may be a copper electrode,which is applied, for example, by sputtering.

The electrical characteristics of the capacitors with an integrationdensity of 150 pF/mm² are shown in FIGS. 19 to 22.

FIGS. 19 to 22 show the dependence of the capacitance (19), of the phase(20) and of the loss factor (21) on the frequency and leakage currentcharacteristics (22) of the capacitors with an integration density of150 pF/mm² as a function of the capacitance value (or electrode area).

The yield of functioning substrates was >>90% on a substrate analogousto example 1. FIG. 19 shows the essentially frequency-independentbehavior of capacitance of a capacitor of area 1 mm². The loss factorwas in the range of 0.05-0.3 and is, as shown in FIG. 21, likewisevirtually independent of the frequency. FIG. 22 shows the leakagecurrent measured for capacitors with different electrode areas. Themeasurement results are essentially independent of the capacitance valueand hence of the electrode area. In addition, the currents measured arecomparable to those in example 2, FIGS. 6 and 7. FIG. 23 shows the ohmicresistance measured in the equivalent circuit diagram of the realcapacitors at different integration densities or at different effectivemean polymer layer thicknesses (180-200 nm for 150 pF/mm² and 500-600 nmfor 50 pF/mm²). The resistance is the same in both cases.

FIG. 23 shows the resistance of the capacitor to DC current at differentintegration densities.

The fact that the resistances measured in FIG. 23 have the same profilesshows that the essential contribution to the ohmic overall resistance ofthe capacitor to direct current is made by the self-assembled monolayer.The quality of the SAM layer deposited is therefore paramount firstlyfor the good insulation properties and secondly for a good yield of theactual capacitors. FIG. 24 shows that the process has low dynamics.After an insertion time of 10 seconds, the contact angle is only 1.1°less than after 10 minutes, and 1.9° less than after one hour. The anglethen remains, after repeated measurements, at a mean of 135°±0.8°, evenafter 72 hours of insertion time of the samples in the SAM solution.

FIG. 24 shows the dependence of the contact angle measured after the SAMcoating of the circuit board on the insertion time of the sample in thesolution.

In a further embodiment, the polymer layer is in the form of ABS(acrylonitrile-butadiene-styrene). This is structurally seeded withpalladium by standard methods and the outer electrodes of copper ornickel are deposited electrolessly.

Here, capacitors which can be produced in a parallel process on aprepreg or other common circuit board substrates are described for thefirst time. Thereafter, the prefabricated capacitor layer can beintegrated into the circuit board, which results in a space/cost savingfor the surface of the circuit board.

The topography of the capacitor is extremely small in relation to theroughness of the base substrate. The related art assumes that it is notpossible to deposit self-assembled monolayers on copper. It is shownhere that self-assembled monolayers (SAMs) with phosphonic acid anchorscan be deposited very efficiently and rapidly on copper after the coppersurface has been cleaned appropriately. This layer constitutes theactual insulation layer of the capacitor. For mechanical stabilization,a thin polymer layer is applied to the SAM. The outer contact may takevarious forms.

The invention has been described in detail with particular reference topreferred embodiments thereof and examples, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention covered by the claims which may include thephrase “at least one of A, B and C” as an alternative expression thatmeans one or more of A, B and C may be used, contrary to the holding inSuperguide v. DIRECTV, 69 USPQ2d 1865 (Fed. Cir. 2004).

The invention claimed is:
 1. A self-assembled monolayer capacitorcomprising: a copper or copper containing substrate; an organic compoundhaving anchor group and a head group connected by a linker group, theanchor group attaching directly to the substrate to form theself-assembled monolayer thereon, the anchor group containing at leastone of a phosphonic acid and a phosphonic acid derivative, the linkergroup containing a polyether chain; a thin polymer layer attached to thehead group; an outer electrode formed on the thin polymer layer, whereinthe anchor group is attached directly to the substrate without anon-copper oxide.
 2. The self-assembled monolayer capacitor as claimedin claim 1, wherein the anchor group comprises a long-chain phosphonicacid.
 3. The self-assembled monolayer capacitor as claimed in claim 1,wherein the anchor group comprises a decyl- to octadecylphosphonic acid.4. A capacitor comprising: a copper or copper-containing substrate; anelectrode; and an electrically insulating self-assembled monolayer,comprising an organic compound and positioned between the electrode andthe substrate, the organic compound comprising an anchor group and ahead group connected by a linker group, the head group serving forattachment to a next layer, the anchor group containing at least one ofa phosphonic acid and a phosphonic acid derivative, which attachesdirectly to the substrate without a non-copper oxide.
 5. The capacitoras claimed in claim 4, wherein the anchor group comprises a long-chainphosphonic acid.
 6. The capacitor as claimed in claim 4, wherein theanchor group comprises a decyl- to octadecylphosphonic acid.
 7. Thecapacitor as claimed in claim 4, wherein the anchor group comprises aphosphonic acid described by the general formula CH₃—(CH₂)_(n)—PO(OH)₂,where n=8-25.
 8. The capacitor as claimed in claim 4, wherein the linkergroup is a polyether chain (—O—CH₂—CH₂—O—)_(m) where m is from 1 to 20.9. The capacitor as claimed in claim 4, wherein a thin polymer layer isattached to the head group as the next layer.
 10. The capacitor asclaimed in claim 9, wherein the polymer layer is comprises apolyhydroxystyrene.
 11. The capacitor as claimed in claim 10, whereinthe polyhydroxystyrene has a molar mass in the range from 500 to 15,000.12. The capacitor as claimed in claim 10, wherein the polyhydroxystyrenehas been cross-linked by melamine-co-formaldehyde.
 13. The capacitor asclaimed in claim 9, wherein the polymer layer comprises at least onepolymer selected from the group consisting of an epoxide, an acrylate, aurethane and a carbonate.
 14. The capacitor as claimed in claim 9,wherein the polymer layer has a layer thickness in the region of lessthan 1 μm.
 15. The capacitor as claimed in claim 9, wherein the polymerlayer comprises a polymer having a molar mass in the range from 1000 to1,000,000.
 16. A component which is based on organic electronics,comprising: a circuit board, a prepreg or a blank, wherein the blank,circuit board or prepreg serves as a substrate and has a copper orcopper-containing surface; and an electrically insulating self-assembledmonolayer, comprising an organic compound, the organic compoundcomprising an anchor group and a head group connected by a linker group,the head group serving for attachment to a next layer, the anchor groupcontaining at least one of a phosphonic acid and a phosphonic acidderivative, which attaches directly to the copper or copper-containingsurface of the substrate without a non-copper oxide.
 17. The componentas claimed in claim 16, further comprising a polymer layer attached tothe head group as the next layer.
 18. The component as claimed in claim16, further comprising an outer electrode formed of copper or nickel.19. The component as claimed in claim 16, wherein the anchor groupcomprises a long-chain phosphonic acid.
 20. The component as claimed inclaim 16, wherein the anchor group comprises a decyl- tooctadecylphosphonic acid.